1. Field of Invention
The present invention relates to a brace of a building structure, and more particularly to an energy-dissipation unit used in the brace for reducing the destruction to buildings and constructions caused by earthquake.
2. Description of Related Arts
More and more multi-store buildings and high-rise buildings are constructed, so that seismic resistant design attracts continuous efforts from researchers. The conventional seismic resistant design focuses on “resisting”, which has drawbacks of high cost and low reliability. Therefore, a structure controlling technology is developed. The structure controlling technology includes active structure controlling technology and passive structure controlling technology. Energy dissipation brace is a common passive structure controlling technology, which can be used for the earthquake effect-reduction of newly built construction and existing construction.
Ordinary energy dissipation brace is not used for load-bearing, and can be disposed between columns or shear walls. Ordinary energy dissipation brace is formed by installing dissipation joint or damper to the ordinary brace. The brace including dissipation joint or damper does not take loads in service or under frequent earthquakes. In case of intense earthquake, when the main structure members are subjected to large displacements or high velocity, the energy dissipation braces start to slide or rotate, which will increase the damping or friction that can dissipate the energy inputted from vibration of base so as to reduce seismic action and protect the main structure from severe damage. At present, many kinds of energy dissipation braces have been developed, which can be grouped into three categories: friction energy dissipation brace, viscous damper (VD) and buckling restrained brace (BRB).
The friction energy dissipation brace absorbs energy by the sliding of metal plates; the VD is made of viscoelastic material. VD is related to the velocity, which dissipates energy inputted from vibration of base via the damping produced by the transformation of the viscoelastic material. BRB utilizes the hysteretic performance of metals, which yield into plastic range to absorb energy. The conventional energy dissipation brace is to connect dissipation element or damper to the ordinary brace, or is made of high ductile metal materials, which has drawbacks of high cost, inconvenience to be installed, get maintenance or be replaced, and high precise requirement in manufacturing and constructing.